Air ducts of various lengths and sizes are used to transfer clean, filtered air from an air filter through an engine air intake system. It is also well known to use air ducts to transfer cooled or heated air from within the engine compartment to the passenger compartment of an automobile. Air ducts are widely used in other applications wherever air or any other gas-like substance is transferred between components.
Air ducts have been formed by using a rubber molding process. Although the rubber molded air ducts are effective, they are considered too heavy for use in vehicles requiring lighter weight to improve fuel efficiency. Additionally, rubber molded air ducts are bulky and difficult to mold in the serpentine configurations desired for automobiles which have limited space in the engine compartment.
An alternative to using a one-piece rubber molded air duct is a two-piece construction which utilizes a thermoplastic blow molded tubular body with an injection molded rubber cuff, sometimes called a seal, affixed to an end thereof. Although lighter and more compact than a rubber air duct, the two-piece construction has its own inherent problems. The tubular body must be mechanically secured or adhesively bonded to the cuff to affect a connection therebetween that can withstand the vibration and heat within an engine compartment.
Seals or cuffs are typically made of a very soft elastomeric polymer material. The cuffs are attached to a connection port in many ways including, but not limited to, thermoplastic welding, worm-gear clamping, or overmolding. Overmolding is the most robust process for forming the cuff because it creates a uniform melt bond to the hard polymer duct.
In a specific application, air ducts are used to supply air and/or exhaust gases to a turbocharger. In such applications, it has been determined that introducing a swirling motion to the air or gases, which are fed to the turbocharger, improves the efficiency thereof. Introduction of the swirling motion can be achieved by incorporating vanes into the air duct. However, depending upon the placement of the vanes in the duct the swirling motion may be minimized or lost. It is also known to use swirl vane rings that are separately injection molded and snap-fit into the air duct. However, these rings tend to rattle and/or fall out during assembly or shipping and may also become dislodged during use, thus minimizing the effectiveness of the turbocharger.
Therefore, there is a need in the art for a swirl vane cuff that creates a desired air flow pattern but which also provides a standard cuff clamp seal. There is also a need for a swirl vane cuff that is overmolded directly to the air duct and which creates a leak-proof chemical bond between the two.